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By T. E. Gray

This report describes the preparation characteristics of the more significant coal beds in Allegheny County, Pa. It is one of a series planned to determine coals suitable for producing metallurgical coke, either as mined or after beneficiation. More than 7 million tons of coal was produced in Allegheny County in 1957. Of this, more than 5 million tons was cleaned mechanically in nine cleaning plants. The Bureau of Mines estimated that, as of January 1, 1953, more than 384 million tons of recoverable coal remained in the county in beds 28 inches or thicker.

Jan 1, 1959

By Maria I. De Rosa, Charles D. Litton

The National Institute for Occupational Safety and Health (NIOSH/PRL) con­ducted a series of large-scale experiments to evaluate the effectiveness and safety of various concentrations of an inert gas mixture (CO2,8%;N2, 50%; Ar, 42%) for preventing and sup­pressing cab ?res. Comparison of concentrations effectiveness in yielding safe times has led to the choice of an optimum gas mixture concentration, discharged in the cab through a muf?ed nozzle system, for the development of a dual cab ?re inerting system. Of note is that safety training programs, including the synchronization of performed tasks, need to accompany this technology to enhance operator’s ef?ciency and safety during ?re emergencies within the safe times yielded by the cab ?re inerting system. Cab ?res are caused by the ignition of ?ammable vapors and mists (ball of ?re) that penetrate the cab during prolonged hydraulic ?uid and fuel ?res, and electrical malfunctions involving other cab combustible materials. Often, these ?res force the operator to exit the cab under hazardous conditions during a time needed to perform emergency tasks. Hence, it is important to provide the operator, not only with an engine fire suppression system (dry chemical powder), but also with a cab ?re protection system, effective both in preventing the ignition of ?ammable vapors in the cab, and suppressing cab material ?res.

By Roy L. Soderberg

Ground support for metal, nonmetal, and coal mines was examined through fill placement with a pneumatic stower to increase extraction, reduce ground pressures, and improve general mine safety. Several pneumatically stowed stope-fill products were tested to determine the effects of specific gravity, gradation, moisture, and impact velocity on the in-place density of the stowed fill. Hydraulic sand filling has now served the mining industry for several decades but because of the low density does not always provide ample support to the hanging wall; therefore, the sill and crown pillars sometimes build up excessive stresses that are detrimental to mining. Cementation of a dense fill adjacent to a pillar to allow 100-pct extraction of the pillar, or a fill that can be placed without the use of water and where water is a detriment to rubber-tired mining equipment, was found to be a possible use of pneumatic fill. Placing of coal mine washery products into abandoned underground workings is another possibility in order to completely eliminate surface impoundments.

Jan 1, 1976

By Jacqueline H. Jansky

The Bureau of Mines conducted a study to determine the relation-ship between geologic features and linears. Cleats, kettlebottoms, and roof rolls were mapped and superimposed on the linear plots for a coal mine in West Virginia. No clear relationships were evident. This may be due, in part, to the mining practice of leaving head coal, which obscures geologic features that may exist in the roof. Future studies should concentrate on mines where roof is extensively exposed.

Jan 1, 1982

By F. N. Kissell, C. D. Litton

Abstract-This study predicts the level of smoke that miners might meet while trying to escape a coal mine fire and describes how smoke would impede their safe escape. For this study, the authors assumed that miners exit through an escapeway adjacent to the burning entry, that some air would leak from the burning entry to the escapeway. The following conclusions were made: • A very low amount of air leakage to the escapeway can produce a critical level of visual obscurity from smoke. This shows that intake airways may be as susceptible to smoke visibility problems as return airways. • This critical level of smoke obscurity is reached much before a critical level of carbon monoxide is reached. • Small fires can cause a severe sensory irritation that further limits vision. Thus, reliable eye protection is very important. These results show that methods to guide miners through dense smoke will contribute greatly to saving lives during mine fires.

By an Slo, J. J. Forbes

"INTRODUCTION This is the first of a series of information circulars dealing with the control of roof and the prevention of accidents from falls of rock and coal. These circulars are being published to focus attention of the coal-mining industry on this most prevalent source of fatalities and injuries and to present factual information that should be helpful in reducing loss from these causes.Records of fatal accidents in the coal mines of the United States, from all causes, have been kept since 1906; during this period approximately 30,000 men have been killed by falls of rock and coal in the bituminous-coal mines, and more than 7,000 men have lost their lives in the Pennsylvania anthracite mines from the same causes. From 1906 to 1930, about 900 men were killed annually by falls of rock and coal in bituminous-coal mines, and about 200 men were killed annually in anthracite mines during the same 25-year period. From 1931 to the present time, the number killed annually from falls of rock and coal has averaged more than 500 men in bituminous-coal mines and about 125 men in Pennsylvania anthracite mines.Numerically the record of accidents from falls of rock and coal shows improvement, but on a percentage basis and on a million-man-hours-of-exposure basis little, if any, improvement has been made during the past 40 years. The cold fact is that, year after year, about 50 percent of all those killed in coal mines in the United States lose their lives from falls of rock and coal."

Apr 1, 1948

By H. E. Harris

It has long been recognized that one of the principal ways of combating dust in coal mines is by means of water sprays. However, spray systems, currently in use, clog or plug frequently, thereby reducing the effectiveness of dust control aid, in turn, possibly increasing the health hazard to mining personnel. Moreover, the maintenance and replacement of spray system components, e.g., nozzles and filters, can be expensive in terms of direct costs of labor and material, and the consequent loss of production. Recognizing these problems, the Bureau of Mines sponsored a research project on the "Development of a Non-Clogging Water Spray System"; this project was carried out by Eastern Associated Coal Corp. The overall objective of this project was to develop a non-clogging water spray system suitable for use in underground coal mines. Since most of the dust formed is at or near the working coal face, emphasis was placed on face equipment such as a continuous mining machine. To accomplish this objective, a two-phase project was carried out. The first phase involved determining the causes of spray nozzle and spray system clogging, determining the availability of spray nozzles or systems that could be modified to be non-clogging, and developing a non-clogging water spray system. Phase two was concerned with the fabrication and the laboratory and field testing of a non-clogging system. In each phase, there were both laboratory and field investigations, and the results of these investigations are presented in this report.

Jan 1, 1975

By Fred N. Kissell

In This Chapter [The explosibility of methane gas mixtures Effect of pressure and temperature on explosibility Less common sources of methane ignitions The amount of methane stored in coal Forecasting the methane emission rate Layering of methane at the mine roof When the recirculation of mine air is hazardous The importance of higher air velocity in preventing methane explosions and Mine explosions, barometric pressure, and the seasonal trend in explosions] Dealing with methane in mines and tunnels requires knowledge of the circumstances under which dangerous accumulations of methane are likely to occur. This knowledge involves the properties of the gas itself, an awareness of where these accumulations are likely to occur, and facts on how methane mixes safely into the mine air. The other chapters in this handbook address the handling of methane under a variety of specific circumstances, such as at continuous miner faces or coal storage silos. This chapter addresses some broad concepts that serve as a foundation for the suggestions provided in other chapters. THE EXPLOSIBILITY OF METHANE GAS MIXTURES Methane entering a mine or tunnel often enters as a localized source at high concentration. Figure 1–1 depicts a cloud of methane being diluted into a moving air stream. In this illustration, methane enters the mine from a crack in the roof. As the methane emerges from the crack, it progressively mixes with the ventilation air and is diluted. In the event that this progressive dilution reduces the concentration from 100% to 1%,2 as shown in Figure 1–1, the methane passes through a concentration range of 15% to 5%, known as the explosive range. In the explosive range, the mixture may be ignited. Above 15%, called the upper explosive limit (UEL), methane-air mixtures are not explosive, but will become explosive when mixed with more air.

Jan 6, 2006

By C. E. Jordan

Domestic cobalt resources are relatively large, but low grade. The full potential for cobalt production from domestic sources is at least 19.4 million lb of cobalt per year exclusive of offshore resources. A summary of the cobalt processing technologies for the major domestic resources is presented in this Bureau of Mines report. The processing technologies for the Blackbird, Madison Nine, Duluth Gabbro, iron ore pyrite, laterites, and manganese sea nodules are nearly complete, but the economics are not favorable. Research on these resources should be limited to approaches that promise to cut the total processing costs by at least 50 pct. The most promising sources of cobalt are the spent copper leach solutions and siegenite from the Missouri lead ores. Research on cobalt processing from these two sources needs to be completed.

Jan 1, 1988

By L. B. Berger

Studies showing the effect of mixing hot exhaust gases with tie intake air of a four-stroke-cycle Diesel engine are described. The results indicate a marked increase in carbon monoxide in tip exhaust gases, a decrease in oxides of nitrogen, and no significant effect on aldehydes. The increase in carbon monoxide was greater at higher fuel-air ratios and was caused partly by the increase in fuel-air ratio end partly by the decrease in oxygen concentration resulting when exhaust has was added. The application of these results to the use of Diesel engines underground is considered.

Jan 1, 1940

By H. R. Babitzke, H. Kato, R. E. Siemens

An investigation was made to provide further information for evaluating columbium- hafnium alloys for use as high - temperature structural materials . The columbium- hafnium system was investigated between 700 ° and 2,400 ° C by melting point , thermal analysis , X - ray diffraction , electrical resistivity , and metallographic techniques . The equilibrium diagram is the beta isomorphous type , with columbium tending to stabilize the beta phase . Addition of 60 atomic percent columbium stabilizes the beta phase at 700 ° C. The allotropic transformation temperature of hafnium is 1,750 ° ± 20 ° C. A minimum melting point occurs near 75 atomic percent hafnium .

Jan 1, 1964

By James E. Norman

[The flotation of mica is mentioned frequently in the literature, but most of the references have dealt with the recovery of mica by the old anionic collectors. The first use of the new cationic reagents indicated their superiority as collectors in the flotation and agglomerate tabling of micas, feldspars, guartz, clay, and other acidic minerals, but the separation of these minerals from each other necessitated of the study of the flotation of each mineral.]

Jan 1, 1941

By Daryl E. Radcliffe

The Bureau of Mines studied the displacement of the roof in a portion of the Bear coal mine near Somerset, Colo, Horizontal-and vertical-displacement gages were installed in a five-entry section during normal room-and-pillar mining procedures. Monitoring of the roof continued until this section was mined out. Displacement measurements in combination with known time lapses between mining and bolting operations indicate that once support is achieved, the length of unsupported time does not appear to affect long-term roof stability in the mine under investigation.

Jan 1, 1978

By d&apos, Kathleen J. Amico

THIS summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S mineral production also is included.

Jan 1, 1964

By d&apos, Kathleen J. Amico

THIS summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S mineral production also is included.

Jan 1, 1964

Lignite constitutes approximately 97 percent of the near-surface coal resources in Texas. The most significant bituminous resources are in the north-central and southern parts of the state. Coal reserves in Texas are estimated to be 13.7 billion tons, about three percent of U.S. coal reserves. The average thickness of coal seams mined in Texas is approximately eight feet. Texas gained primacy when its regulatory program was conditionally approved February 16, 1980; the program was fully approved June 18,1980. The state's Abandoned Mine Lands program was approved June 23,1980.

Jan 1, 1992

By James E. Norman

[The flotation of mica is mentioned frequently in the literature, but must of the references have dealt with the recovery of mica by the old anionic collectors. The first use of the new cationic reagents indicated their superiority- as collectors in the flotation and a. agglomerate tabling of micas, feldspars, quartz, clay, and other acidic mineral, but the separation n of these minerals from each other necessitated study of the flotation of each mineral.]

Jan 1, 1941

By J. E. Pahlman

As part of its goal to minimize the requirements for mineral commodities through conservation and substitution, the Bureau of Mines is conducting research to determine the resistance of alumina refractories to corrosion by alkali-containing slags that could result from burning of the abundant Western lignites in metallurgical operations. Static corrosion tests were performed at 1,000° to 1,350° C and dynamic tests were performed at 1,400° to 1,600° C to investigate the stability of refractory specimens in slag environments. In general, the degree of refractory attack increased with decreasing alumina content in the refractory and with increasing alkali content of the lignite ash. The parabolic kinetics observed in static tests suggested that a reaction product layer is formed through which ionic diffusion must occur to sustain the reaction with the refractory material. The linear kinetics observed in dynamic tests in high-viscosity slags indicated a shearing of the reaction product layer by viscous slags. The observed lesser attack of refractories by low-viscosity slags can be explained on this basis. Two 99-percent-alumina refractories and two 90-percent-alumina refractories formed an expanded protective layer with the more viscous slags but not with the less viscous slags. Corrosion of 90-percent-alumina refractories increased exponentially with temperature. In refractories with the same nominal alumina content, those that contain a combination of a-Al203 and mullite (3A1203?2Si02) have better corrosion resistance than those containing a combination of a-Al203, cristobalite (Si02 mineral), and mullite. In alkali environments (1,300 to 1,400° C), 90-to 99-percent-alumina refractories are recommended for use as furnace linings.

Jan 1, 1980

By J. R. Thoenen, Hugh D. Pallister

"INTRODUCTION The Stone Hill Copper project resulted from the recommendations made in the war minerals report on this deposit by engineers of the Bureau of Mines 4/ and a similar report of the Geological Survey. 5/ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of domestic mineral resources to the end that they make the greatest possible contribution to the national security and economy. The Mining Division, Lowell E. Moon, chief, conducts preliminary examinations, does the actual investi¬gative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.This report was prepared under the supervision of Paul M. Tyler, former regional engineer, Eastern Region, and is based on the examination and investigation of the deposit by Hugh D. Pallister, mining engineer, made under the immediate supervision of Richard W. Smith, former District Engineer for Alabama and Mississippi.The report was rewritten and prepared for publication by J. R. Thoenen, chief, Tuscaloosa Branch, Mining Division.LOCATION AND ACCESSIBILITYThe Store Hill copper mine is about• 12 miles south of Heflin, the oounty seat of Cleburne County, Ala. Heflin, a town with a population of approximately 1,700, is the nearest shipping point for freight and express. It is on the Southern Railway, between Birmingham and Atlanta. A rural mail route passes within quarter of a mile of the mine. Paved reads from Heflin lead to Atlanta, Birmingham, and Montgomery. The country Toads leading from Heflin are well-maintained but are practically inaccessible during inclement weather. The road crossing the property within a hundred yards of the mine needs grading and repairing (see fig. 1)."

Apr 1, 1948

By J. E. Chilton, T. Mal

Methane monitoring at the mine face is essential to assure a safe work environment in underground coal mines. Machine-mounted methane monitors must be used to continuously monitor methane levels during mining. Monitors used on mining machines must be approved by MSHA and properly maintained to provide protection for workers (30 CFR 75.342). To provide protection the instrument must give accurate readings of current methane levels. Accuracy is maintained by calibrating the instrument with a standard gas at least once every 31 days. Instrument “response time” determines how quickly measurements will change to reflect current concentrations. At present there are no criteria for measuring the response time for a ma-chine-mounted methane monitor while underground. This study examined a procedure for measuring the response time of a machine-mounted methane monitor. Response times were measured using methanometers obtained from three different manufacturers. The effects of the measurement technique and methanometer sensor head design on response time measurements are investigated. Techniques for reducing variation in response time measurements are discussed.